Question: What is the greatest common factor of $20$ and $2$ ? Another way to say this is: $\operatorname{gcf}(20, 2) = {?}$
Solution: The greatest common factor is the largest number that is a factor of both $20$ and $2$ The factors of $20$ are $1$ $2$ $4$ $5$ $10$ , and $20$ The factors of $2$ are $1$ and $2$ Thus, the greatest common factor of $20$ and $2$ is $2$. $\operatorname{gcf}(20, 2) = 2$